AMAG most commonly refers to one of two things: AMAG Pharmaceuticals, a drug company that traded on the NASDAQ under the ticker symbol AMAG until 2020, or anti-MAG neuropathy, a rare nerve condition caused by antibodies that attack a specific protein in the body. Which one you’re looking for depends on whether you arrived here from a finance search or a medical one. Here’s what you need to know about both.
AMAG Pharmaceuticals
AMAG Pharmaceuticals was an American drug company focused primarily on treating iron deficiency anemia in adults. Its flagship product, Feraheme, was an intravenous iron medication first approved by the FDA in June 2009 for adult patients with chronic kidney disease. The drug works by delivering iron wrapped in a carbohydrate shell that gets absorbed by immune cells in the liver, spleen, and bone marrow. Once inside those cells, the iron is released and either stored or shuttled into the bloodstream to help build new red blood cells. By 2013, Feraheme was generating an estimated $71.5 million in annual revenue.
Over the following years, AMAG expanded beyond iron therapy. In 2014, the company acquired Lumara Health (formerly KV Pharmaceutical), which brought Makena into its portfolio. Makena was a hormone injection intended to reduce the risk of preterm birth, though the FDA ultimately withdrew its approval in April 2023 after confirmatory studies failed to demonstrate a clear benefit. AMAG also acquired Cord Blood Registry for $700 million in 2015 and announced plans to acquire Perosphere Pharmaceuticals in late 2018.
The company also marketed Vyleesi, an injectable treatment for hypoactive sexual desire disorder (HSDD) in premenopausal women. The drug works by influencing brain chemicals involved in mood and sexual arousal.
AMAG Pharmaceuticals stopped trading publicly in November 2020 when it was acquired by Covis Pharma. The AMAG ticker symbol on NASDAQ is no longer active.
Anti-MAG Neuropathy
Anti-MAG neuropathy is a rare autoimmune nerve disorder. “MAG” stands for myelin-associated glycoprotein, a protein found on the protective coating (myelin) that surrounds nerves. In this condition, the immune system produces antibodies that mistakenly target MAG, gradually damaging the myelin and disrupting nerve signals. The result is a slowly progressive form of nerve damage classified as a demyelinating neuropathy.
The condition is rare. A nationwide survey in Japan found a prevalence of just 0.28 per 100,000 people, with roughly 0.05 new cases per 100,000 each year. It predominantly affects adults over age 50.
Symptoms
Anti-MAG neuropathy tends to affect sensation more than strength. The most common early symptom is numbness or tingling in the hands and feet, typically on both sides of the body in a symmetrical pattern. Over time, you may notice difficulty walking, a noticeable tremor in the hands, and some weakness in the extremities. Because sensory nerves are hit harder than motor nerves, many people experience significant problems with balance and coordination before they notice any real loss of muscle power. The progression is usually slow, unfolding over months to years rather than days or weeks.
How It’s Diagnosed
Diagnosis involves blood tests that detect the presence of anti-MAG antibodies, along with nerve conduction studies that show a pattern consistent with demyelination (damage to the nerve’s insulating layer). Doctors also look for an abnormal protein in the blood called an IgM paraprotein, which is often the source of the harmful antibodies.
Treatment Options
There is no cure for anti-MAG neuropathy, but treatments aim to slow progression and manage symptoms. Conservative approaches include pain management, physical therapy, and occupational therapy to help with daily tasks affected by numbness or coordination problems. For more aggressive treatment, intravenous immunoglobulin (IVIG) is sometimes used to temporarily modulate the immune response.
The most studied targeted therapy is rituximab, a medication that depletes certain immune cells responsible for producing the harmful antibodies. In clinical trials, about 36% of patients treated with rituximab showed measurable improvement in disability scores at 8 to 12 months, compared to 10% on placebo. Self-reported outcomes were even more striking: roughly 84% of rituximab-treated patients rated their condition as stable or improved, versus 45% on placebo. Physical quality-of-life scores also improved significantly. Rituximab reduced both overall IgM levels and anti-MAG antibody levels in the blood, which aligns with its mechanism of targeting the immune cells that produce those antibodies.
Rituximab is not a guaranteed fix. Many patients stabilize rather than improve, and the condition can continue to progress despite treatment. But for a disease with limited options, it represents the strongest evidence-based therapy currently available.